Demand for good quality housing is increasing, with most pressure in urban areas. However, there is a balance between development and preserving much-needed greenspace and greenbelt land. Derelict former industrial sites could provide a solution, but expensive and energy-intensive remediation of contaminated sites can discourage their re-use.
Bioaccessibility describes the potential for a substance to be absorbed by an organism currently and over time. Applying a bioaccessibility assessment to contaminated land allows for a less conservative, more accurate risk assessment with a focus on human health impacts.
Contaminated brownfield land
Soil contamination can be a major barrier to re-use of brownfield sites, particularly former industrial sites.
Sites that contain organic contaminants – such as those from petroleum products, solvents and pesticides – are usually assessed for ‘total contaminant concentration’. While this highlights some of the adverse impacts on health, it is a very conservative approach and can deter redevelopment.
- The Government needs to meet local housing requirements through finding suitable land in the right places. By using bioaccessiblity assessments, more brownfield land could be re-designated as suitable for housing.
- Bioaccessibility methodologies can also help to push a more sustainability-driven planning policy, as more former industrial sites are considered safe for development, and demand for development sites increases.
- Brownfield sites are often well-connected and central, leading to healthier cities.
- Bioaccessibility or in vitro methods account for the proportion of a contaminant that if ingested and digested, will be available for absorption by the body.
- Bioacccessibility is already used to assess remediation options for soil contaminated by heavy metals such as lead and zinc, and PAH (polycyclic aromatic hydrocarbon) contamination from incomplete combustion of fossil fuels including vehicle emissions.
- Bioaccessibility methods improve the accuracy of contaminated land assessments and adopt a less cautious approach.
Our research demonstrates that bioaccessibility techniques can be applied more widely to the assessment of soils afflicted by organic compounds closely related to heavy industry, manufacture, transport and construction.
Bioaccessibility testing could lead to an increase in the number of contaminated sites re-designated as usable, encouraging greater re-use of brownfield sites, and a more sustainable and healthier urban environment.
Our project paves the way for bioaccessibility testing to become the standard approach for sites affected by organic contaminants. The method can be applied globally as such compounds are common, and could also be used to assess new types of contaminant.
New bioaccesssibility methods
We assessed two distinct methods with a wide range of soil and contaminant profiles. Both are repeatable, robust laboratory assessment techniques, demonstrating that bioaccessibility testing can be applied to organic contaminants, in a field dominated by established methods to assess bioaccessibility in inorganics and metals.
- The project has also led to a better understanding of PCB bioaccessibility – we have now produced a background survey of PCB concentrations in central London.
- We have also demonstrated the benefits and opportunities of close interdisciplinary research, with researchers from soil science, geochemistry, organic chemistry and sustainability work together, at the University of Reading and British Geological Survey (BGS).
In addition to more accurate risk assessments with a focus on human health impacts, bioaccessibility testing also leads to:
- Less landfill waste & energy use from remediation.
- Lower remediation costs for developers & government agencies
- Reuse of urban brownfield sites for homes, avoiding urban sprawl and long commutes.
- Reduced need for testing on living organisms.
Next steps for contaminated land community
- Exploring the findings and establishing professional processes & training
- Adoption by regulators
Next steps for researchers
- Further work in validation, followed by consultation with contaminated land professionals and regulators to encourage adoption of the methods.
- Developments through computer simulation assessments, or methods to accurately assess risks from dermal or inhalational contact with both organic and inorganic contaminants.